QEMM

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Quarterdeck Expanded Memory Manager (QEMM) was a popular DOS memory manager made by Quarterdeck Office Systems from the late 1980s to the late 1990s. It helped DOS and Windows programs run more smoothly by managing memory beyond the 640K limit, using EMS, XMS, and other memory technologies, and by relocating parts of DOS like the kernel and command interpreter. It could load drivers before itself and still use its Stealth feature to improve memory availability.

QEMM also offered Windows support through MagnaRAM, a memory- compression tool that kept data in RAM and compressed idle data to speed up writes to disk. It included utilities for hardware information and optimizing driver loading. The last version, QEMM 97, matched the year-based naming and worked with Windows 95/98, but DOS memory management became less needed as RAM grew and Windows and DOS programs evolved.

In practical terms, QEMM could free up a large amount of conventional RAM (about 635K) and could share up to 256MB of XMS/EMS memory. It introduced features like ROM relocation and Stealth D*Space to keep more memory available for programs. Over time, many users switched to built-in managers like HIMEM.SYS and EMM386 or moved to newer systems, making QEMM less essential.